The present invention relates to a toner supply device for electrophotographic equipment which develops a latent image electrostatically formed on an image carrier by using toner.
An electrophotographic copier, facsimile machine, printer or similar equipment using an electrophotographic process is extensively used. This kind of equipment forms a latent image on an image carrier and then develops it by a developer which is generally implemented by toner. The toner is sequentially consumed in a developing section and, therefore, fed from a toner tank in an adequate manner. Toner has to be fed to the toner tank also, because the toner in the tank sequentially decreases with the lapse of time due to the consumption in the developing section. Various approaches have heretofore been proposed for the supply of toner from the toner tank to the developing section and to the supply of toner to the tank itself. One of them uses a toner tank having a size large enough to accommodate a great amount of toner. A problem with this scheme is that the great amount of toner stored in the toner tank is apt to solidify due to changes in temperature and humidity. Should the solidified toner accumulate in the tank, the amount of toner supply to the developing section would become irregular while the charging characteristic of the toner would be degraded. On the other hand, when the toner tank is reduced in size in order to reduce the amount of toner accommodatable therein and is operated in combination with a toner cartridge or a toner container which is a conventional implementation, the toner cartridge or the toner container has to be replaced frequently increasing the burden on the operator. Further, the toner cartridge cannot be increased in size beyond a certain limit when it comes to electrophotographic equipment of the type having an optical unit above the toner tank.